Hydraulic pump valve spacer



Nov. 21, 1961 w. R. LEISSNER 3,009,423

HYDRAULIC PUMP VALVE SPACER Original Filed Sept. 23, 1957 2 Sheets-Sheet1 IN V EN TOR.

W E (aw/v56 BY Arr 'y s 0v 21, 1961 w. SSSSSSSS ER 3,009,

United States Patent 3,009,423 HYDRAULIC PUMP VALVE SPACER William R.Leissner, Milwaukee, Wis., assignor, by mesue assignments, to AppliedPower Industries, Inc., a corporation of Wisconsin Original applicationSept. 23, 1957, Ser. No. 685,441, n'ow Patent No. 2,945,444, dated July19, 1960. Divided and this application Oct. 19, 1959, Ser. No. 847,344 2Claims. (Cl. 103-225) This invention relates generally to hydraulicpumps and finds particular utility in such pumps of the multiple pistontype.

In a pump of this type, the frequency of cyclic operation between theinlet and outlet check valves of the pistons is very critical and anyaxial shifting of the pumping cylinder relative to the piston destroysthis desired frequency.

An object of this invention is to provide an inlet check valve spacer ofsuch construction and shape that the inlet flow pattern through thepiston is greatly improved and turbulence therein substantially reduced.The result isa particularly efiicient pumping unit. The invention alsoprovides a novel means for assembling the spacer in a fixed andpredetermined correct axial position.

These and other objects and advantages will appear hereinafter as thisdisclosure progresses, reference being had to the accompanying drawings,in which:

FIGURE 1 is an axial cross-sectional view through a hydraulic pumpembodying the features of this invention;

FIGURE 2 is a transverse cross-sectional view taken (fan line 2--2 ofFIGURE 1, through the discharge maniold;

FIGURE 3 is a transverse cross-sectional view taken on line 33 of FIGURE1, and showing the inlet valve spacers in the discharge end of thepumping pistons;

FIGURE 4 is an axial cross-sectional view, on an enlarged scale, throughan inlet check valve spacer shown in FIGURES 1-3 made in accordance withthis invention and showing the flow pattern therethrough;

FIGURE 5 is another view, similarly enlarged, of the spacer shown inFIGURE 4; and

FIGURE 6 is a still further enlarged end view of the spacer shown inFIGURES 4 and 5, and taken generally from line 6-6 of FIGURE 5.

Referring more particularly to the drawings, the pump housing comprisesa cylinder barrel section 10 secured by circumferentially spaced capbolts 11 to a drive section 12 and having an *O-ring seal 13therebetween. A chamber 14 is defined within the housing into which asupply of fluid is introduced through the inlet port 15.

A drive shaft 16 extends through the housing and is suitably journalledin anti-friction bearings 17 in section 12 and its endis piloted in theanti-friction bearings 18 located in the barrel section 10. A shaft seal19 prevents leakage of fluid from the housing.

A wobble plate 20 is secured to the drive shaft by a key 21 and has aneccentric surface 22. An axial thrust bearing plate 2 3 is located inchamber 14 and a thrust ring 24 having a plurality of anti-frictionbearings 25 therein is located between the bearing plate and the wobbleplate.

An anti-friction ring member 27 is mounted on an eccentric portion 28 ofthe drive shaft 16 and is adapted to rotatably bear against theeccentric surface 22. A hardened steel plate 29 is also mounted oneccentric portion 28' for rotation in respect thereto.

The cylinder barrel section 10 of the pump housing has a plurality ofcircumferentially spaced bores 30 extending therethrough which arearranged in parallelism and in an axial direction. These bores are allconnected together by a common manifold 31 which places them in com- 2munication with the common discharge port 32 (FIG: URE 2).

A replaceable cartridge assembly 35 is inserted in each bore 30 andaccurately secured therein against either axial or rotationaldisplacement as follows. The sleeve 36 of the cartridge has a recess 37in its periphery which is adapted to snugly receive the dowel portion38' of the cap screw 39. A seal 40 prevents any fluid leakage to theoutside of the pump. The screw 39 accurately positions the sleeve in anaxial correct predetermined position and also prevents any rotationalmovement of the sleeve. A plug 41 has a portion 42 which threadablyengages the end of sleeve 36. When the plug is tightened, its collarportion 43 bears against the outside of the pump housing and because ofthe'clearance between the collar 43 and the sleeve, draws the sleeve tothe right, as viewed in FIGURE 1. As a result, the sleeve is drawn uptight against the locking dowel, 38, thus securing the sleeve inposition. An 'O-ring seal 44 seated on the portion 46 of the plug actsto seal against fluid leakage. Another -0-ring seal 45 is locatedbetween the sleeve 36 and its bore 30 to prevent fluid leakagetherebetween. To remove the entire cartridge assembly it is onlynecessary to withdraw the dowel portion 38.

The cartridge assembly also includesa cylinder 47 in the sleeve 36 whichforms a pumping chamber for the piston assembly 48 reciprocatinglymounted therein. The cylinder 47, of the cartridge assembly shown inFIG- URES 1 and 2, is placed in fluid communication'with the manifoldpassage 31 by means of the cross bore 50 in the sleeve 36.

An outlet check valve is provided for each pumping unit and includes acheck ball 52 which is adapted to seat against the ring seat 53 locatedin the counterbore 54 of the sleeve. The seat 53 is held against axialdisplacement by the looking ring 55' which is threadably engaged in thesleeve. A spring 56 bears against the ball 52 to yieldingly hold itagainst its seat and also bears against the inner end of plug 41. Aprojection 57 is formed integrally on the inner end of the plug and actsas a locating guide for the spring 56 surrounding it.

The piston assembly 48 may also be considered as part of the cartridgeassembly and includes the piston 58 which has a hemispherical end 59, onwhich is held captive by snap ring 60, and universally tiltable slipper61. The slippers are urged firmly against the wobble plate assembly bythe spring 62 which acts between the shoulder 63 of the sleeve and thecollar 64, which is secured to the piston by snap ring 65.

As viewed in FIGURE 1, the piston 58 has a series of bores 67, 68, 69and 70 which progressively decrease in diameter in that order and whichare all connected together. A pair of cross ports 71 place the pumpinlet chamber 14 in fluid communication with bore 70.

An inlet check valve is provided within each piston which serves toadmit fluid to the pumping chamber 47 when the piston is moved to theleft (FIGURE 1) during its suction stroke. When the piston delivers itspumping stroke the inlet valve is closed. This inlet valve comprises acheck ball 72 which sealingly seats against the shoulders 73 formed bythe juncture of bores 68 and 69. A spring 74 urges the ball to thisseated position. The spring also bears against the inlet valve spacer'75 which is fixedly and accurately positioned in bore 67 within thelimits predetermined by the snap ring 76 and the shoulder formed by thejunction of bores 67 and 68. The exact axial location of the snap ring76 relative to the ball 72 is predetermined and it is an easy matter toassemble this piston without error. In other words, it is unnecessary tofirst screw the spacer into contact with the ball and then back it oil apredetermined number of revolutions where it would be locked in place.

The spacer 75' thus accurately locates the maximum travel of the checkball in the opening direction. The extent of this ball movement isimportant as the frequency of cyclic operation between the inlet ball72; and the outlet ball 52 is critical to the proper high speedoperation of these pistons and the smooth flow of fluid therethrough.

The spacer made in accordance with this invention is of such shape andconstruction that a highly improved flow pattern of fluid therethroughhas been achieved. The flow through this particular location must bewithout turbulence if maximum efiiciency of the pumping unit is to beobtained.

Referring to FIGURES 4, and 6, the spacer 75 includes a tubular portion77 which has integrally formed at its leading edge of the flat,centrally located, ball contacting stem 78. The stem is of smallerdiameter and width than the internal bore 79 of the tubular portion 78.The stem 78 is cut away at its central part adjacent the tubularportion, to form an opening 80 which contributes to the smooth flow offluid through the spacer. As shown in FIGURE 6, a substantiallysemi-circular opening 81 is provided at either side of the spacerthrough which the fluid flows. By splitting the flow with the openingsof this shape, a diametrically opposed flow has been obtained which hasno turbulence. The result has been a marked increase in the efiiciencyof these pumping units.

Various modes of carrying out the invention are contemplated as beingwithin the scope of the following claims particularly pointing out anddistinctly claiming the subject matter which is regarded as theinvention.

What is claimed and desired to be secured by Letters Patent is:

1. A piston assembly for a hydraulic pump comprising,

a piston having a passageway extending axially therethrough, saidpassage defined by bores of difierent diameters so as to form first andsecond shoulders, an inlet check ball in said passage and adapted toseat against said first shoulder, a spacer for said ball comprising atubular portion mounted in one of said bores and seated at one endagainst said second shoulder, a snap ring mounted in said one bore andsecurely holding said spacer against said second shoulder, the wall ofsaid one bore being imperforate, a stem extending from said tubularportion and having a free end against which said ball is adapted to hearwhen in a fluid admitting position, said stem being of generally fiatcross section and forming at its junction with said tubular portion oneach of two diametrically opposed sides a fluid passageway ofsubstantially semi-circular shape when viewed axially along said spacer.

2. An assembly as defined in claim 1 including a spring mounted aroundsaid stem and contacting said check ball to urge the latter toward saidfirst shoulder.

References Cited in the file of this patent UNITED STATES PATENTS1,523,575 Beloit Jan. 20, 1925 1,530,827 Gunn et al. Mar. 24, 19251,582,624 Bacon Apr. 27, 1926 1,999,693 Hill Apr. 30, 1935 2,243,978Reader June 3, 1941 2,345,634 Schnell Apr. 4, 1944 2,612,837 MidgetteOct. 7, 1952 2,633,802 Parilla et al. Apr. 7, 1953 2,713,829 BeachamJuly 26, 1955 2,849,208 Skipwith Aug. 9

